Pyrazolinium compounds as herbicides

ABSTRACT

This invention provides for 1,2-dialkyl-3,5-disubstituted and 3,4,5-trisubstituted pyrazolinium salts, a method for the preparation of the said compounds, and a method for controlling undesirable plant species therewith.

United States Patent [191 Cross PYRAZOLINIUM COMPOUNDS AS HERBICIDES[75] Inventor: Barrington Cross, Rocky Hill, NJ.

[73] Assignee: American Cyanamid Company,

Stamford, Conn.

[22] Filed: July 1, 1974 21 Appl. No.: 484,515

[52] US. Cl 260/311; 260/310 R; 71/92 [51] Int. Cl. C07D 231/12; AOlN9/22 [58] Field of Search 260/310 R, 311

[56] References Cited FCREIGN PATENTS OR APPLICATIONS 2,260,485 6/1973Germany [451 Dec. 9, 1975 I,3l5,825 5/1973 United Kingdom PrimaryExaminerDonald B. Moyer Attorney, Agent, or FirmI-Iarry I-I. Kline [5 7]ABSTRACT 10 Claims, N0 Drawings PYRA ZOLINIUM COMPOUNDS AS HERBICIDESThis invention relates to pyrazolinium salts repre sented by theformula:

N-RZ

provided that when R is hydrogen, at least one of R and R is a memberother than phenyl; X represents an anion having a charge of from 1 to 3,and preferably 1 or 2; n is aninteger selected from 0 and l; m is aninteger selected from I, 2 and 3; and Y and Z each represent membersselected from the group consisting of hydrogen, halogen, nitro, cyano,alkyl C,C alkoxy C,-C,, and CF Illustrative of the anions which aresuitable for use in the present invention may be mentioned, for example,halides, such as chloride, bromide or iodide; acetate; sulfate,hydroxide; hydrogen sulfate; methyl sulfate; benzene sulfonate; C -Calkoxy benzene sulfonate; C,--C alkyl benzene sulfonate, preferably atoluene sulfonate, such as p-toluene sulfonate; nitrate; phosphate;carbonate; hydrogen carbonate; alkane sulfonate C,C perchlorate;

wherein R is halogen, methyl, halomethyl or dihalomethyl; R and R areeach halogen; R, is hydrogen or methyl; and R is chlorine or methyl.

With regard ot pyrazolinium salts of the present invention, it is to beunderstood that certain multivalent anions such as sulfate, phosphate,and the like, may have associated with them a cation in addition to thepyrazolium cation, as for example, a proton or an alkali metal oralkaline earth metal. For simplicity, such anused herein, isintendedtomean ions are portrayed as being unionized although they proobably arein fact further ionized. Typical representations arezNaSOf, KPOf, M poH5041 7 P0 and the like. y

Unless otherwise defined, the term halogenf as dine and fluorine.

above sturcture, wherein R and R are each methyl; R

is hydrogen, methyl, methylthio or methoxy; and R R X and m are asdescribed above. 1 'Still more preferred are compounds depicted by-the'above formula, wherein R and R are each methyl;R is hydrogen, methyl ormethoxy; R and R each repre-', sent a member selected from the groupconsisting of phenyl, monohalo phenyl, monomethylphenyl,- dimeth-.ylphenyl and cycloalkyl C -C provided that whenR is hydrogen at leastone of R and R is a member other than phenyl; X is an anion having asingle charge; and m is l. V

The invention, while relating to the compounds described by formula (I)above, also relates to a method for the preparation of said compoundsand to a method for controlling undesirable plant species with saidformula (l) eoumpounds and derivatives thereof. The latter saidderivatives are represented by the given formula, but also includecompounds wherein R is hydrogen, R and R are phenyl, and X and m are asdefined above.

Advantageously, the pyrazolinium compounds of the invention can beprepared by several procedures. One procedure, hereinafter referred toas Procedure A, involves the condensation of an a,B-unsaturated ketonewith an equimolar amount, and preferably an excess of from 1 to 2 moleequivalents ofa l,2-dialkylhydrazine salt. This reaction is preferablyconducted in the presence of a protonic solvent such as a lower alcoholC -C or acetic acid, and usually requires elevated temperatures of fromabout 50C to 150C, and preferably C to C, and an extended reactionperiod of from about 2 hours to two weeks. A 24- to 48-hour refluxperiod is frequently employed; however, a shorter reflux period may beused. The pyrazolinium products can be isolated from unreacted chalconeby virture of their water solubility. isolation can be achieved byevaporation of the solvent from the reaction mixture, dissolution of theremaining residue in water, and extraction of impurities with ether. Theappropriate salt of the pyrazolinium ion can then be obtained from theaqueous solution by evaporation of the water. The anion of thel,2-dialkylhydrazine salt will be the anion of the pyrazolinium salt.Ion exchange chromatography may be used to exchange the anion of thepyrazolinium salt. The exchange may be affected by treating theinitially formed salt with an ion exchange resin. Among the suitable ionexchange resins, one may mention a strong base organic anion exchanger,such as Dowex l-x8. illustrative exchangers employ quaternary ammoniumsalts. Where the resin is supplied as the salt of an anion other thanthat desired, it is pretreated with an aqueous solution of a salt of thedesired anion. For example, if the resin is supplied as a quaternaryammonium chloride and it is desired to produce a pyrazolinium bromide,one would pretreat the resin with hydrobromic acid.

Other modifications of the anion in the pyrazolinium salt can also beaffected. For example, a pyrazolinium chloride can be convenientlyconverted to the corresponding bromide or iodide by treatment withaqueous chlorine, bromine, io-

with chloroform and then removal of the chloroform by evaporation.

The reaction of Procedure A may be graphically illustrated as follows:

where R,, R R R R and X are each as defined above. As shown, when R =RProcedure A gives the predominant product as (lb) involving reactionfirst at the carbonyl carbon center. Thus, this procedure can 4 tion ofthe appropriate pyrazolium compound. This procedure is, hereinafter,referred to as Procedure B, and involves treatment of a pyrazolium saltwith a reducing agent such as lithium aluminum hydride or sodiumborohydride. The reduction with sodium borohydride is generallyconducted in the presence of a solvent such as alcohol. Other suitablesolvents include C -C saturated alcohols, isopropyl alcohol beingpreferred. This reaction is generally carried out at an elevatedtemperature between about 20C. and l00C. using equimolar amounts of thepyrazolium compound and the reducing agent. The reduction with lithiumaluminum hydride is conducted in other solvents such as 15 diethylether, dimethyl ether, methylethyl ether, tetrahydrofuran, in thetemperature range of from 20C to 100C.

After the reduction, the resulting 3-py razoline is probe used toprepare isomers (la) or (lb) by selection of 35 tonated with anappropriate acid, HX, to give the the appropriate starting chaleone.

Pyrazolinium compounds of the present invention depicted by formula (I)can also be prepared by reducpyrazolinium salt. This reaction isgraphically illustrated as follows using sodium borohydride as arepresentative reducing agent:

1 N\N R (9 I a 2 e NaBH $1 1 N\ R5 N\N R 2 I 2 R3 R R3 ax ax 1 1 l to N2 2 l e X X R3 R4 R3 where R,, R R R R and X are each as defined above.

The 3-pyrazolines (Ila and llb) may be isolated directly from thereduction, if desired, by avoiding pro- 5 tonation in the work-upprocedure.

Among the compounds which can be prepared by one or both of the aboveprocedures are:

S-Benzyl-l ,2-dimethyl-3-phenyl-2-pyrazolinium dide;

3-Cyclohexyl-l ,2-dimethyl-5-phenyl-2-pyrazolinium iodide;

3-Cyclohexl -enyl-l ,2-dimethyl-5-phenyl-2- pyrazolinium iodide;

S-Cyclohexyl-l ,2-dimethyl-3-(p-fluorophenyl)-2- pyrazolinium methylsulfate; 1

3,5-Dicyclohexyl-l ,2,4-trimethyl-2-pyrazolinium perchlorate;

S-Cyclohexyl-l ,2-dimethyl-3-pentyl-2-pyrazolinium chloride;

l,2- Dimethyl-3,5-di( 2,4-xylyl)-2-pyrazolinium chloride;

3Cyclohexyl-l ,2-dimethyl-5-phenyl-2-pyrazolinium iodide;

3 ,S-Dicyclohexyl-l ,2-dimethyl-2-pyrazolinium p-toluenesulfonate; V

l,2-Dimethyl-3-( Z-methylcyclohexyl )-5-phenyl-2- pyrazolinium iodide;

l,2-Dimethyl-3-( 3-cyanophenyl)-5 phenyl-2- pyrazolinium iodide; I l,2,4-Trimethyl-3 ,5-diphenyl-2-pyrazolinium iodide; 5-(m-Fluorophenyl)-l,2-dimethyl-3-phenyl-2- pyrazolinium bromide;

5-(o-Fluorophenyl)-l ,2-dimethyl-3-phenyl-2- pyrazolinium methylsulfate;

5-(p-Fluorophenyl)-l ,2-dimethyl-3-phenyl-2- pyrazolinium hydrogensulfate;

3-(p-Fluorophenyl)-1,2-dimethyl-5-phenyl-2- pyrazolinium perchlorate;

l,2-Dimethyl3-o-tolyl-5-p-tolyl-2-pyrazolinium iodide;

l ,Z-Dim'ethyl-S-o-tolyl-3-p-tolyl-2-pyrazolinium methyl sulfate;

1,2-Dimethyl-3,5-dim-tolyl-2-pyrazolinium methyl sulfate;

3-(p-Chlorophenyl)-l ,2-dimethyl-5-phenyl-2- pyrazolinium benzenesulfonate;

3-Cyclohexyl-l ,2,4-trimethyl-5-phenyl-2- pyrazolinium perchlorate;

l,2-Dimethyl-3,5-di-o-tolyl-2-pyrazolinium iodide;

5-Anisyl-l ,Z-dimethyl-3-phenyl-2-pyrazolinium perchlorate;

l,2-Dimethyl-3-(p-nitrophenyl)-5-phenyl-2- pyrazolinium iodide;

1,2-Dimethyl-3-phenyl-5-thienyl-2-pyrazolinium io- 55 dide;

l,2-Dimethyl-3-phenyl-5-m-tolyl-2-pyrazolinium iodide; and

1,2-Dimethyl-5-phenyl-3-m-tolyl-2-pyrazolinium iodide.

The compounds of the present invention, as represented by formula (1)above, and derivatives thereof wherein R is hydrogen and R and R ,arephenyl, are highly effective as herbicidal agents. They are particularlyeffective when used as postemergence herbicides and applied to thefoliage of undesirable plants at a rate between about 05 pound and 10pounds per acre, and preferably from 0.5 pound to 4 pounds per acre.

Surprisingly, we have found the compounds of this invention to beselective wild oat herbicides effective for the contnrol of Avena fatua,Avena ludoviciana and Avena sterilis in the presence of crops such asbarley, wheat and rice. They are also selective for controllingbroadleaf weeds such as mustard, pigweed, velvetleaf and morningglory.

For application of the formula (1) pyrazolinium salts to the foliage ofthe undesirable plant species, the salts are generally formulated aspostemergence herbicidal compositions by admixing a herbicidal adjuvantwith a herbicidally effective amount of the salt. Suitable adjuvantsinclude one or more conventional solid or liquid carriers, diluents andformulation aids, particularly surfactants.

The active compounds may be formulated as dusts, dust concentrates,wettable powders or water-miscible concentrates; however, thewater-miscible concentrates are especially advantageous.

Dusts are readily prepared by grinding together aboutl% to 25% by weightof the active agent with from about 99% to by weight of a solid diluentsuch askaolin, attapulgite, diatimaceous earth, or the like. Dustconcentrates are prepared in similarfashion excepting that about 25% to95% by weight of the active agent is ground with about 75 to 5% byweight of the diluent. v I

wettable powders are prepared in the same manner i as the dustconcentrates excepting that about 1% to 5% by weight of a dispersingagent such as sodium lignosulfonate, or the sodium salt of condensednaphthalene sulfonic acid is blended with the mixture and about 1% to 5%of a surfactant, such as polyoxyethylated vegetable oil or an alkylphenoxy polyoxyethylene ethanol is also blended with the formulation. Inpractice, the powder is mixed with water and applied to the plantfoliage as an aqueous spray.

Water-miscible concentrates are prepared by dissolving from 15% to 70%of the compound in to 30% of a water-miscible solvent, such as wateritself or another polar water-miscible solvent, such as 2- methoxyethanol, methanol, propylene glycol, diethylene glycol, diethyleneglycol monoethyl ether, formamide and methylformamide. Application ofthe material is made by adding a predetermined quantity of thewater-miscible concentrate to a spray tank and applying the concentrateas such or in combination with an additional quantity of water or otherpolar solvent as a liquid spray.

The invention is further illustrated by the examples set forth below.These examples are provided only by way of illustration and are notintended to be limiting on the invention.

EXAMPLE 1 Preparation of l,2-Dimethyl-3,5-diphenyl-Z-pyrazolinium iodideProcedure A CO-CH=CH CH3NH-NHCl-l HI An absolute ethanol solution ofsym-dimethylhydrazine dihydriodide [sym-dimethylhydrazine dihydriodideis prepared from sym-dimethylhydrazine dihydrochloride (13.3 g, 0.1mole) in ethanol by refluxing with an excess of potassium iodide (33.2g, 0.2 mole) for 3 hours], is added to an absolute ethanol suspensionofchalcone (15.6 g). The reaction mixture is heated to reflux withconstant stirring and maintained there for 25 18 hours. After allowingthe reaction mixture to cool to room temperatue, the solvent is removedby evaporation, and the resulting mixture stirred with an aqueouspotassium iodide solution. The resulting solid is filtered and dried togive 5.95 g (21%), melting point 175C to 176C ofl,2-dimethyl-3,5-diphenyl-2-pyrazolinium iodide.

EXAMPLE 2 Preparation of 1,2-Dimethyl-3,5-diphenyl-2-pyrazoliniumperchlorate Procedure B (a) NaBH (b) HC10 Sodium borohydride (1.95 g) isadded to a partial solution of 1,2-dimethyl-3,S-diphenylpyrazoliummethyl 185C of sulfate (17.75 g) in isopropanol (700 ml). The reactionmixtureis heated to reflux with stirring and maintained 20 at reflux for6 hours. After allowing the reaction mix- EXAMPLE 3 35 Following eitherProcedure A or Procedure B, as described in Examples and 2 above, andemploying (1) the apropriate a,B-unsaturated ketones and symmetricaldialkyl hydrazine salt, or (2) the appropriate 1,2-

dialkyl-3,S-diSubstituted pyrazolium salt, yields the compounds reportedin Table I below.

Melting Point Analysis C Calculated Found Method 175-176 (dec.)

(dcc.)

64809 8 609 7'39 846 .15 A .9 068.0 64957 4699 462 556 5 5 22 5 3 506472 2873 2873 6 0 .5 5500. 0 54957 472 472 656 5 5 3 5 3 5 CHU N CHNCHN CHN 9 9 7 9 4 3 w 6 4 .x 4 4 8 7 5 6 A A A A 4 m C 1. 1 .1 3 H F C FH H H H F H H H H C C C C v TABLE I-bo ni inucd Prcpai'ation ofPyrazolinium Salts having the Structure:

Melting Point Analysis C Calculated Found Method C H N [66-168 (dea) CIOLow melting solid EXAMPLE 4 The postemergence herbicidal activity ofthecompounds of the present invention is demonstrated by the followingtests, wherein a variety of monocotyledonous and dicotyledonous plantsare treated with test'compounds dispersed in aqueous acetone mixtures.In the tests, seedling plants are grown in jiffy flats for about twoweeks. The test compounds are dispersed in 50/50 acetone/water mixturescontaining 0.5% Tween" 20, a polyoxyethylene sorbitan monolauratesurfactant by Atlas Chemical industries, in sufficient quantity toprovide the equivalent of about 10 pounds per acre of active compoundwhen applied to the plants through a '/1 Difference in (irowth RatingSystemfrom the Check 0 No cllcct I) l Possible effect l H) 2 Slighteffect ll -Z5 3 Moderate effect 2640 5 Definite injury 4lhll t1Herbicidal effect 01-75 7 Good herbicidal effect 76)() 8 Approachingcomplete kill )I-99 9 Complete kill I00 4 Abnormal growth, that is, adefinite physiological malformation but with an over-all effect lessthan a 5 on the rating scale.

Based on visual determination of stand. size. vigor. chlorosis. growthinalforma lion and overall plant appearance.

spray nozzle operating at 40 psi for a predetermined time. Afterspraying, the plants are placed on green- Plant Abbreviations: housebenches and are cared for in the usual manner, LA Lambsquarters(Chenopudium album) commensurate with conventional greenhouse prac- MUMustard (Brassicu kaher) tices. Two weeks after treatment, the seedlingplants 30 Pl Pigweed (Amaranlhus retroflexus) are examined and ratedaccording to the rating system RAG Ragweed (Ambrosia artemisiif'olia)provided below. The data obtained are reported in MG Morningglory(Ipomoca purpurea) BAA Bar- Table ll below, where it can be seen thatthe com nyardgrass (Echinolchlua crusgalli) pounds are highly effectivefor the control of lamb- CR Crabgrass (Digitaria sanguinalis) squarters,mustard and pigweed; specific compounds GRF Green foxtail (Selariaviridis) are also highly effective against ragweed, morningglory W0 Wildoats (Avena fatuu) and velvetleaf. VL Velvetleaf (Abutilon theoplzaras)TABLE ll Postermergence Herbicidal Activity Tredtment Annual WeedsStructure lb/Acre LA MU Pl RAG Mo BA CR GRF wo Vl.

t0 9 9 5 s 2 2 2 3 *s 2 t0 9 9 9 0 3 r 0 2 0 *s 6 It) 9 9 9 2 9 s 3 6 79 TABLE II-continued Postermergence Herbicidal Activity Annual Weeds LAMU, Pl RAG MG BA CR GRF W0 v1.

5 week data EXAMPLE 5 The pronounced selective postemergence herbicidalactivity of the compounds of this invention is demonstrated in thefollowing tests. The test procedure employed is essentially the same asthat described for the postemergence tests, described in the precedingexample; however, thecompoundsare applied at.rates of from 0.5 pound to9 pounds per acre, and crop plants such as barley, wheat and rice areused to determine selectivity. Wild oat data are taken at five weeksalong with crop readings.

Data obtained arereported inTable III below, where it can be seen thatthe compounds of the present invention are highly effective forcontrolling mustard, pigweed, velvetleaf, wild oats and morningglory,but cause little or no injury to barley (Hordeum vulgare); and

v with selected compounds, little or no injury to wheat (Triticumvulgare) and/or rice (Oryza sativa).

Additional Plant Abbreviations:

BR Barley (Hordeum vulgare) MU Wild Mustard (Brassica kaber) WH Wheat(Triticum vulgare) RI Rice (Oryza sativa) TABLE 111 SelectivePostemergence Herbicidal Activity Treatment Structure lb/Acre BR MU WHPl BA CR GRF WO MG Rl VL 4 0 9 l 9 O 2 l 8 .l 3 9 l O 9 l 9 0 2 l 8 l 23 e 0.5 0 7 0 3 0 2 1 I 8 l 2 3 0 C10 4 0 8 3 9 2' 9 9 8 5 0 5 1 O S 0 l0 5 l 7 l 0 S 0.5 0 5 O O I 0 3 0 3 l 0 5 H 4 O 9 6 9 I l 0 3 l 6 9 I c3 e 1 0 9 5 5 0 0 0 s 0 3 2 I 0.5 O 5 5 0 0 0 0 9 0 2 3 mam:Ill-continued Selective Postemergence Herbicidal Activity Structurelb/Acre .Treatment v BR MU WH Pl BA CR GRF W0 MG Rl VL I claim: I. Acompound having the formula:

provided that when R; is hydrogen at least one of R and R is a memberother than phenyl; X represents an anion having a charge of from I to 3;n is an integer selected from 0 and l; m is an integer selected from I,2 and 3; and Y and Z each represent members selected from the groupconsisting of hydrogen, halogen, nitro, cyano, alkyl C C, alkoxy C C andCF;,.

2. A compound according to claim 1, wherein R and R are each methyl; Ris a member selected from the group consisting of hydrogen, methyl,methylthio and methoxy; and R R X and m are as defined in said claim 1.g

3. A compoundaccording to claim 1, wherein R and R are each methyl; Rrepresents a member selected from the group consisting of hydrogen,methyl and methoxy; R and R each represent member selected from thegroup consisting of phenyl, monohalophenyl, monom ethylphenyl,dimethylphenyl and cycloalkvl C -C provided that when R, is hydrogen atleast one of R and R is a member other than phenyl; X is an anion havinga single charge; and m is l.

4. A compound according to claim 3, wherein R is hydrogen; and R and Rare monomethylphenyl.

5. A compound according to claim 3, wherein R is hydrogen; and R and Rare cycloalkyl C -C 6. A compound according to claim 3, 1,2-dimethyl-3-phenyl-S-(o-fluorophenyl)-2-pyrazolinium perchlorate 7. A compoundaccording to claim 3, 1,2-dimethyl-3- o-tolyl-S-p-tolyl-2pyrazoliniumiodide.

8. A compound according to claim 3, l,2-dimethyl-5-phenyl-3-m-tolyl-2-pyrazolinium iodide.

9. A compound according to claim 3, 3-(p-fluorophenyl)-l,Z-dimethyl-S-phenyl-2-pyrazolinium iodide.

10. A compound according to claim 3,l,2,4-trimethyl-3,5-diphenyl-Z-pyrazolinium iodide.

1. A COMPOUND HAVING THE FORMULA:
 2. A compound according to claim 1,wherein R1 and R2 are each methyl; R4 is a member selected from thegroup consisting of hydrogen, methyl, methylthio and methoxy; and R3,R5, X and m are as defined in said claim
 1. 3. A compound according toclaim 1, wherein R1 and R2 are each methyl; R4 represents a memberselected from the group consisting of hydrogen, methyl and methoxy; R3and R5 each represent member selected from the group consisting ofphenyl, monohalophenyl, monomethylphenyl, dimethylphenyl and cycloalkylC3-C7, provided that when R4 is hydrogen at least one of R3 and R5 is amember other than phenyl; X is an anion having a single charge; and m is4. A compound according to claim 3, wherein R4 is hydrogen; and R3 andR5 are monomethylphenyl.
 5. A compound according to claim 3, wherein R4is hydrogen; and R3 and R5 are cycloalkyl C3-C7.
 6. A compound accordingto claim 3, 1,2-dimethyl-3-phenyl-5-(o-fluorophenyl)-2-pyrazoliniumperchlorate.
 7. A compound according to claim 3,1,2-dimethyl-3-o-tolyl-5-p-tolyl-2pyrazolinium iodide.
 8. A compoundaccording to claim 3, 1,2-dimethyl-5-phenyl-3-m-tolyl-2-pyrazoliniumiodide.
 9. A compound according to claim 3,3-(p-fluorophenyl)-1,2-dimethyl-5-phenyl-2-pyrazolinium iodide.
 10. Acompound according to claim 3,1,2,4-trimethyl-3,5-diphenyl-2-pyrazolinium iodide.